But a new study from the University of Surrey is challenging that assumption. The research, published in Food and Energy Security, has found that while vertical farms can out-yield traditional lettuce farms more than twentyfold and use vastly less water, they still carry a heavier carbon footprint.
The findings underscore a central tension in sustainable agriculture: in solving one problem – climate vulnerability, water scarcity, and land use – are we worsening another?
For lead author Michael Gargaro, a postgraduate researcher at the University of Surrey’s Centre for Environment and Sustainability, the study was about taking a hard, evidence-based look at one of agriculture’s most talked-about technologies.
“This study was undertaken to understand what the differences in environmental impact are between traditional field farming of lettuce and a novel approach using vertical farming,” Gargaro explains. “Vertical farming is often seen as being a greener alternative, and this study took place to understand whether that was true, using the cultivation of lettuce as a case study.”
The researchers conducted a “cradle-to-store” life cycle assessment – tracking emissions from all stages of lettuce production, from planting materials and energy use to packaging and delivery. They compared commercial vertical farm operations in the UK with conventional field farms on both mineral and peat-based soils in the UK, as well as a farm in Spain, which together represent the lion’s share of the country’s lettuce supply.
The results were revealing: while the vertical farms produced an astounding 97 kilograms of lettuce per square metre – compared to just 3.3 kilograms in the field – they also emitted significantly more greenhouse gases.
Even when powered entirely by renewable electricity, vertically farmed lettuce generated 0.93 kilograms of CO₂ equivalents per kilogram of lettuce, compared with 0.57 kilograms for field-grown lettuce.
It’s a surprising result, Gargaro admits. “Our research shows that while the technology can bring higher yields and reduce water use, it currently comes with a higher carbon cost. The challenge now is to make vertical farming more energy-efficient and better integrated with renewable systems, so that it can become a truly sustainable solution.”
Much of the environmental burden comes from the energy intensity of vertical farming systems. LEDs, climate control, and ventilation run around the clock to replicate and regulate conditions nature provides for free.
Gargaro notes that even with clean energy, the sheer electricity demand remains a sticking point. “Integrating vertical farming with renewable energy systems significantly reduces the environmental impact,” he says. “But even when we modelled the system using renewable energy sources, the impact was still higher than traditional agriculture.”
The study found that if a vertical farm relied on the UK’s current grid electricity mix, emissions ballooned to five times higher than field farming.
The other unexpected contributor was the material used to grow the crops. Many vertical farms rely on jute fibre plugs, fibrous blocks that replace soil and support the plants’ roots. These, the researchers discovered, carry a surprisingly high environmental impact due to their production and disposal processes.
By switching to alternative materials like coconut coir, a byproduct of the coconut industry, vertical farms could cut their land footprint by more than 95 percent. To be clear, this was land area for sourcing of materials and inputs, as well as for energy production.
“Small changes in these sorts of materials could reduce the impact of vertical farming systems to bring them in line or lower than field farming,” Gargaro adds.
Despite its challenges, the study doesn’t dismiss vertical farming – it reframes it. The technology, Gargaro argues, isn’t necessarily about replacing field agriculture but about securing food resilience in a changing world.
“I don’t believe the benefits of vertical farming lie in its ability to grow food,” he says. “It lies in its ability to secure food resilience in an ever-more precarious world, and its ability to free up swathes of land which can be used for other purposes is key for hitting many national and global targets – be it more food production, bioenergy crops, afforestation, or simply more housing and infrastructure.”
That point is particularly salient for the UK, where around 95 percent of lettuce is imported from Spain during winter months. Climate change is making that model increasingly fragile. Spanish growers face mounting pressure from drought and water scarcity, while transport-related emissions add further weight to the carbon tally.
“Vertical farming has the potential to transform food security in the UK, particularly as climate change and seasonal drought place growing pressure on traditional agriculture,” Gargaro notes. “The technology is still evolving, but its ability to produce food locally, year-round, and without reliance on imports is a massive advantage.”
Dr. Zoe Harris, co-director of the Institute for Sustainability and a co-author of the study, agrees. “With around 95 percent of lettuce imported from Spain during the winter months, advances in vertical farming make it possible to secure a year-round supply of fresh produce while freeing up land for restoration, such as peatland and woodland,” she explains. “But to viably compete with field farming, vertical farms must cut their energy use and rethink the materials they rely on.”
The findings come at a turbulent time for the vertical farming industry. Over the past five years, billions have been invested globally in start-ups promising to revolutionize how the world grows its food. Yet several high-profile companies have collapsed under the weight of high energy bills, costly infrastructure, and overambitious scaling.
Gargaro acknowledges that the financial and policy landscape remains a challenge. “At present, there is a lack of financial government support for vertical farming,” he says. “However, the government is funding research projects on vertical farming to provide resilience to the food system. The problem for businesses has been the manner in which they scaled up – too fast and with the wrong technologies – causing many to fail.”
Nevertheless, he remains optimistic about the sector’s direction. “Overall, there has been great success in the UK and globally in raising funds for scaling vertical farming businesses,” Gargaro says. “The key now is smarter, more sustainable growth – optimising systems for energy use, integrating renewable power, and rethinking materials.”
The study doesn’t condemn vertical farming – it provides a roadmap. Reducing carbon emissions from vertical systems, Gargaro stresses, will depend on two levers: energy efficiency and material innovation.
“Reducing the electricity demand of the system, as well as the composition of the electricity used, is critical,” he explains. “We can make substantial progress by integrating on-site renewables like solar or wind, improving LED efficiency, and optimising the control systems that regulate temperature and humidity.”
Materials, too, offer significant room for improvement. “Our research shows that something as simple as switching from jute to coconut coir can have a major impact,” Gargaro adds. “It’s about understanding where those hidden environmental costs are and designing them out of the system.”
The researchers also point to the co-benefits of vertical farming: freeing up agricultural land for restoration or alternative uses, reducing pesticide reliance, and eliminating food miles through urban production. These factors, while harder to quantify in carbon terms, play an essential role in a holistic sustainability assessment.
For now, the message is clear: vertical farming is not yet the low-carbon solution it’s often marketed to be. But neither is it a dead end.
As energy systems decarbonise and technology improves, the gap could narrow quickly. The potential for circular design, renewable integration, and waste heat recovery could transform the energy profile of vertical systems in the years ahead.
“Vertical farming is still in its infancy,” Gargaro reflects. “But with innovation in energy, materials, and system design, it can become a critical component of a sustainable and resilient food system. The question isn’t whether vertical farming can be sustainable – it’s how fast we can make it so.”
The study was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Engineering and Physical Sciences Research Council (EPSRC). ●
Michael Gargaro, a postgraduate researcher at the University of Surrey’s Centre for Environment and Sustainability
Dr. Zoe Harris, co-director of the Institute for Sustainability
